A 4.14 kb fragment containing the Itga2b regulatory region linked to cre cDNA and the SV40 polyA signal was purified and injected into fertilized FVB/N oocytes. Four founders were identified (A,B,C,D). RT-PCR amplified mRNA only in megakaryocytes. Cre activity was identified in megakaryocytes from only two lines A and B.